Guess what I got in the mail!!?? Yup.. mosfets..
I opened the envelope and showed them to my wife.. she said “how do you solder THOSE”?? I said VERY CAREFULLY!!!
Gonna clear my bench.. grab a couple toasted components and become extremely familiar with my hot air station before I even attempt to swap these out.
Lemon .. THANKYOU. I will do my very best, I hope nothing else got. Toasted…
Wish me luck!

You’re very welcome.

Practice a whole bunch first.
Use lots of flux.
Watch some videos to get an understanding of technique- I’m a fan of NorthridgeFix on YouTube:
https://youtube.com/@NorthridgeFix

Check your work under magnification (magnifying glass if you don’t have a digital microscope) and check it with a multimeter prior to powering up. Keep a fire extinguisher handy, and try running up a motor on the bad esc after you’ve replaced the mosfet prior to putting it into a build.

You’ve got this.

You’re gonna hafta play with your hot air station to find out the best airflow setting for it- every hot air station is unique in how hot the coil gets and how much air it blows at a given setting. You want airflow to be fairly low so you don’t blow anything off the board, but moving enough air to heat things up. Try starting out around 15% on your airflow, go up or down from there as needed.

If you find yourself blowing air on a component for a while without it coming loose or without the solder visibly melting- turn up your heat more and slightly increase your airflow.

Also, make sure you are using tweezers that are specifically for SMD work which have a very fine point. I have all 7 of the tweezers that NorthRidge Fix demonstrates in the video linked to below and they are all excellent. I got them all from AliExpress. They each have their own use but the blue Mechanic ones are probably the pair I would get if I was only to get one pair.

In rare cases you can swap different model FET, but in general you shouldn't.

1. Yours is 2 channel. Obviously can't swap with 1 channel.
2. Some need higher gate voltage and/or driver.

The other obvious problem is "dead" time and other such ESC details.
The new FET must be at least as fast and "good" as the others.

But... the board is dead, so its worth a try.

BTW. When the whoop and toothpick craze started, I built a bunch of 3", and even 4" with those cheep 15A, 13A and 20A boartds.
Everything was awesome. Sunshine. Birds chirping. The faint smell of fresh cut grass.
But, within weeks each of the FC died. And the boards are burned beyond repair.
Apparently having 2 FET close together is bad.

If you have fleet of quads, its really good to buy same/similar FC. I have like 2-3 each of JHEMCU GHF411, GHF405 etc. Parts almost the same.
Worst case, 1 becomes donor and can be used to repair others.

Been practicing… the plastic bits don’t take a lot to melt..

Nice.
Now take your soldering iron, solder wick, and a bunch of flux and remove the bulk of the old lead free solder, re-tin the pads with some proper leaded solder, and then practice putting parts back on with hot air (hot air for the chips and larger parts- for little resistors and caps, I’ve found that it’s sometimes easier to just put them back in place with a fine tip soldering iron).

As far as the melted plastic- switch to a smaller nozzle if you have one and try to be more aware of the direction your heat is blowing.

If you have a silicone baking sheet in your kitchen, you can cut off a section of that and use it as a heat shield over plastic parts. (Maybe ask your wife first if she’s the baker in the house.)

AFAIK for FET and small SMD IC repair

1. For troubleshooting you can lift 1 or more pins on a small SMD IC.
2. Tin with lead solder.
3. Use solder wikc.
4. Slowly pry up with exacto knife or fine tweezer tip.

5. To solder FET, its a bit tricky because the ground plane acts as big heatsink.
6. Make sure you use plenty of flux and good high capacity soldering iron.

When using hot air to replace FET, similar problem. Everything else melts and goes flying first.
Its MUCH easier on some boards to remove the adjacent ceramic capacitors first.

Not gonna continue… did plenty of “practice”, cleaning, reinstalling.. I Jumped in..
First, cleaned with alcohol and a brush.. one of the Mosfets broke apart..
Used plenty of solder.. kept the heat even, the broken one come off in pieces.. the other with a burned corner lifted no problem.
More solder, wick tape, cleaned the pads.. one looked fine with a defined pad seperation.. the other.. not so much.. I looked at he mosfet.. clearly a defined separation.
I tried several times to clean the pad, but I believe the damage went deeper then the mosfet.. it was a bad crash into asphalt…
I’ll just keep these nearby if/ when my other aio drops a esc…

Those two large separated pads on the mosfet should be the drain for each channel.

It shouldn’t matter if it is bridged on the board side, as those two pads are both going to be connected to the same motor pad.

Edit- you can verify this by seeing if the two pads that aren’t bridged on the board have continuity. If they do, you’re good.

After further inspection.. the continuity check seems "OK", however the one TINY pad where the most damage was is 'kinda' there but I have to use a sewing needle to get contact. Nothing on the surface. Also, I noticed a couple small components "moved / missing", either from my attempt to clean or from the crash...
Not going to move forward with the "repair" of this board, but will add power, check the other escs... make sure they test good (with a motor), remove the mosfets, and try again...

Sometimes when a mosfet burns out on a board it will properly burn out and either permanently weld itself to the board or damage the pads/trace from the heat.

But hey, if nothing else, you’re learning a new skill, and even if you can’t fix this one, you can now remove all the other mosfets on it and have plenty of spares for the future.

Edit- I don’t know what kind of brush your using to clean, but it shouldn’t be knocking off components. I used an old toothbrush with light pressure.

Brush.. I use a wire wheel on my Dremel …
JK… no a trimmed down acid brush wish alcohol .. just to clean off crud…
Sorry, wish I had better news.. but hey.. if anyone needs Mosfets … I’ve got some…