Amazon Fire tablet without battery

I am using a fire HD8 tablet as a HA dashboard wall mounted (always on) and I have been using it like this with some automations.

Charge when it drops to 20%
Stop charging at 80%
Repeat infinitely

But now the battery doesn’t even last 30 mins anymore and I don’t want to have it on charge all the time, I simply don’t trust it after seeing my laptop battery swell enough to open the case.

So I opened up the table and just disconnected the battery but now it won’t power on while plugged in, I see the amazon logo for about 2 seconds and then nada.

Any idea if there’s a trick to get it to turn out sans battery?

I’m rather doubtful that it will work. Tablets, much like phones, expect to have a battery. It’s part of the power conditioning circuitry itself.

It’s a shame, having to buy a battery only to waste it again and again…

Built in UPS… that’s how I view those sort of things. If you’ve got it on a smart outlet or something (which I assume you do given that you state you’ve been cycling the charging dependent on the charge status) then you’re still actively using the battery.

Yeah I was wondering if someone smarter than me can tell why I can’t simply hook up the 5v USB cable +/- to the battery +/- connector, since the battery is 3.7v-4.2v looks like

I’m trying to do the same thing. and this is what I’ve found out:
Tablet is not like a simple led, which probably need constant current with some voltage requirement. Tablet has a dynamic way to do things, like when started, when streaming video etc, at different time it might require different current.
The voltage requirement is pretty clear, but the peak current requirement is not something u can find printed on battery or tablet manual. Battery can support high peak current(as long as it’s not constant), but your charger may not be able to do it.