Hi @R3st and welcome to the Fairphone community
It’s important to have stated from the start, that you removed the battery while it was charging … which I’m afraid was a silly thing to do. - but thank you for being honest about it! I’ve no idea what the consequences might be (and I think there’s probably few of us who have experience of this … ) so you’ll need specialist support I expect. See the support page.
One thing you can try, is to turn off the phone, disconnect the USB cable, remove the battery and leave the phone with no battery for 24 hours. Then insert a partially charged battery, if you have one, or otherwise fully-charged, and start the phone. Once the phone’s up and running, plug in the USB cable and hope for the best.
You should certainly replace the two missing screws. Ask support about that too, or maybe post a specific request in the forum to see if anyone with a totally dead phone could help. I don’t know whether the screws are the same as in the previous models … I’m sure one of the community members will be able to let us know!
Please do post back here and let us know how you get on. Keep in touch, other people will be posting here with better advice than mine.