I have firmware 5.1.0 with 4 burnt fuses, which were updated from 3.0.2. I didn't follow rajkosto's complicated guide.
Easy method I used:
update switch normally -> put jig on and hold "volume +" -> install AutoRCM -> 5.1.0 with no burnt fuses during update.
1. Insert a exFAT microSD into Switch, Switch will ask to update to use exFAT format microSD. Click "update now", which will update to 5.1.0 normally as Switch should.
2. When Switch is downloading 5.1.0, put RCM jig on, do not remove it. You have to make sure your jig 100% works.
3. When download reaches 100%, it should prompt "installing updates", hold "volume +", do not release it.
4. After firmware install, Switch will restart itself. If you followed step 2-3, Switch will boot into black screen, which is RCM. You can remove jig and release "volume +" now.
5. Send hekate payload to your Switch, install AutoRCM, turn off Switch.
optional: 6. Put CFW files into your microSD. Boot into hekate again to check burnt fuses. Boot into CFW to play "backups"/homebrew, delete Wifi settings.
Pro: Easy, takes about 5 mins - exFAT ready - no PC needed, no driver/files mess on your PC.
Con: Have to update online, which is fine for me - after update, need AutoRCM all the time on 5.1.0. If you turn AutoRCM off, and boot without RCM, the fuses will burn.