comments:
Thanks, ok this means either the battery is completely kaput, or there is a problem with the charging port. You can either just go out and RMA, which will get you a new deck, but if you are not in warranty or RMA is impossible, you can either buy a new battery (this is the one I bought for my own LCD steam deck: https://www.amazon.com/dp/B0DX1T7W61 ) Or have an electronics repair shop diagnose the port and charging port and check if everything is fine on the board--then they will be able to tell you the battery is not working, and you won't have to deal with if a new one will not work, or something. It all depends on the situation where you live, with access to repair shops that are reputable and won't charge you a bunch of money to do a circuit trace.
Open it and see if the battery is a spicy pillow. If it is, buy a replacement on Amazon. I have this one and it works in both OLED and LCD. https://www.amazon.com/dp/B0DX1T7W61 If it's not spicy, disconnect the cable, buy some Deoxit D5, spray it directly into the slot, and see if that helps.