Randomly shut off while on youtube, lost battery screw

First time repairing this, replaced the digitizer. and everything works fine, charges, doesn't drain fast. but it randomly shut off, and im worried its bc of that? or i damaged the connectors but idk how to lift up enough to see as im worried of breaking it or something. Anyone know where to get the screw? just says its 2.3 mm long screw and i looked everywhere online, thanks!