Posted a previous post thats a bit misleading due to my own incomplete re-learning on the RCM/Hekate/Rebuild NAND process. Here is question with all the learning bugs worked out.
Son's switch (v1 unpatched, NAND rebuilt once a few years ago, don't remember how) did an update a couple of months...
Have a v1 that shows black screen after power on or inserting Nintendo charger. No shorts anywhere on system. All first stage boot voltages good. Doesn't boot from SysMMC. Reflowed eMMC 2x without any improvement. Also can not enter RCM mode except for the following sequence
Enter RCM mode
1...
I may try the new ram site, and download more RAM to my Switch. Not sure if ddr3 is the right ram
for it tho. Edit- no it uses floppy Ram, just like @AncientBoi