No power, battery replaced. Next step?

Hi there!

I've been without use of my Switch for a very long time now (almost a year, only got about 2months of use). After spending 3 months trying to contact Latamel (Mexican Nintendo repair centre) and also trying a local repair shop and having no luck with either, I decided to try to repair it myself.

My console has no power whatsoever. I have attempted switching chargers, checking the console with a USB tester (reads in at ~0.40-0.44A) and even tried purchasing a new battery.

I'm considering finding and purchasing an external battery charger to see if the issue is the USB port and/or charge IC (though i don't think it's the USB port due to receiving any amps at all when checking). Give me opinions on if this sounds like a good idea and what I should try next/instead. If at all possible, I'd like to avoid replacing the chip as it's a bit out of my skill range.

Thanks to everyone who replies!