Upgrading my switch EMMC to 128GB

I saw guides online for upgrading the switch NAND, first on gbatemp and reddit, which linked to John Pascoe here: http://pascoe.pw/2018/09/switchnand.html and he quotes http://bbs.duowan.com/forum.php?mod=viewthread&tid=46505080&from=singlemessage
After reading through I convinced myself to give it a try.
I first bought a few blank USB pendrives and EMMC chips from taobao, pre-balled, so that I could try to teach myself how to solder BGA chips with hot air, this also needed a hot air re-work station, so i bought one of those too from Taobao, 50 dollars lighter and with a small stack of dead USB boards I realised that I wouldn't have the nerve to do an expensive EMMC board, so whilst carrying on my expirements on cheap boards, I sent a 128gb chip, the Samsung KLMDG8JENB-B041 linked below, along with a replacement Switch EMMC board, to a professional to be reworked.

I got the board back, backed up my switch, dissassembled the switch (thanks iFixit!), swapped the EMMC boards, keeping my orginal untouched CFW. This means as long as I never go online (delete all the wifi connections), I can always just switch the EMMC back in and it will be as if I never ran any CFW.
After using Paul's modified restore tool with the backup size check removed, I had the Switch booting back up perfectly with the bigger EMMC, however the switch wouldn't see the new size until I extended the size of the partition, but inside the encryption. This was very tricky to do, and I didn't find either of the above links to be entirely complete as to how it was done.

I eventually managed to get it booting, and so had a 128GB switch booting and working perfectly!
As soon as it was working and booting I had a check online and found a Samsung SDINBDA4-256G 256GB module for sale.

I ordered one, and kept testing the 128gb whilst I waited for the shipping to me, then sent it off to the same company to get it soldered by someone a bit more experienced.

For now, 128gb Switch success!

This article was updated on July 19, 2020