Note: many of these older devices are going out of update support. Use Mister Chrome Box UEFI firmware to turn it into a PC, then use an app called Brunch by Sebanc to install Linux with Chrome OS, then you will have play store and updates. Or just run Linux like PopOs! , Ubuntu, Mint, etc or Win10 (I don't recommend Windows unless using a Ghost Spectre, LTSB or LTSC minimal version.) I guess I should add that to do this I used a CH341a and a utility called ASProgrammer from Github to read and write the physical BIOS chip.

Follow this guide to remove the UMD Door PSP 1000 UMD Door Replacement

(Maybe your screws are already missing, due to factory change or previous repair, but to be safe don't pull on door until you verify)