Cant find the YD label one but this one label with 31 is from Rohm part# DTA044EUB
https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/digital/dta044eubtl-e.pdf
You should create an emummc (emulated copy of your Switch internal memory - sysmmc). Then you use sysmmc for you official games and emummc for your unofficial games and homebrew. That way you can play the games you bought online in sysmmc...
If your fuse count is 19 it explain why your OFW wouldn't boot firmware 16.1.0 as it expect firmware 17.0.0 to 18.0.1. Should always keep a copy of your original NAND, you wouldn't have this problem if you have your own NAND backup, using the...
looks good. top side Extra gnd seems unnecessary though.
The two square ground pads under cap could help stopping flex moving Around, I would say keep them.
file transfer can be done through Hekate(even from another switch). Boot 0/1 can be generated from emmchhaccgen on PC with prod.key from the Blue screen console.
If you can't/don't know how to make unpatched switch into RCM mode, you are on your own.
Switch battery voltage max out at 4.23v-ish, 3.9v is pretty much closed to 90% charged, NOT VERY LOW.
Also If you are expecting 15v goes into the battery terminal, I think you would see some popcorn out of your battery BMS board. This battery...
So you are on HOS FW 18.0.0. Hekate 6.1.1 and AMS 1.7.0prelease should be able to support this verison.
I believe you need to rebuild you nand using Tegraexplorer system_wipe to FW18.0.0