Just had another quick skim back over this thread (sorry I should have done this earlier but it is a long one)
I think your first port of call should be to resolve (or just remove for now) the potential fuel gauge issues as your symptoms changing from being alble to boot Hekate only occured once you replaced the fuel gauge again (I’m assuming that this isn’t a seperate LCD conn bent pin issue though) , aftewhich (and assuming it boots Hekate following) I’d check the fuel gauge stats once again in Hekate, if all stats are basically nil like previous then it’s indicating either an issue with the IC itself or the install, if after reinstalling/replacing the IC the stats aren’t reoprted correctly then I would be checking the resistance to ground of your VBatt rail at the battery connector pin/s on the board and letting us know your readings there just in case and following that I’d jump on over to this topic and ensure all relevant fuel gauge lines have continuity to the various corresponding destinations
Also inbetween all that, after removing the Fuel gauge, I would check the resistance to ground on your SYS rail again just incase the bad IC/install was the the cause of the dragged down readings being caused (by the common BQ IE: a fault on VBatt subsequently dragging down SYS for example) further downstream