Unresponsive to all fixes, shows amber light but will not turn on.

Hello! I got a Kindle 3 Keyboard from a friend. She said the battery needed to be replaced, and it was stuck on the “Low Battery” page. No lights came on when charging or switching power button. I replaced the battery no problem (I’ve done this successfully before). After replacement, amber charging light came on when plugged in. I waited for it to charge, then tried to turn it on. No success, so I held the power switch for 20 seconds, then for 30 seconds. Nothing. I held power switch for 30 seconds then held home button for 45 seconds - screen started flashing, but it stayed blank and did not pull up the “Recovery” screen. I held “R” just in case, but nothing happened. Now, switching the power button does absolutely nothing. When plugged in, the amber light still comes on, but power switch does nothing. I opened the back and it looks like everything is properly connected and free of dust, but I’m not enough of a tech person to know if something is wrong back there. The screen connector (thing on the left side/bottom left??) is connected, and the little wire moves when the power button is moved, so that is all working. I don’t know any other way to fix this, but I also don’t know enough to consider it a lost cause just yet. Any help welcome!

Forgot to mention that the screen is currently blank, but you can see (very faintly) the “Low Battery” page, as if it did not completely go blank. I don’t know if this is relevant or not.