dead battery phone wont charge topic

This is a work phone so it basically been off for the past 2 weeks. I knew it was dead so I put it on the charger last night. I wake up this morning get the phone and nothing, wont turn on totally dead still, also its a bit hot. I unplug it and replug it and all I get is the battery icon, the one that shows on the screen for a bit when you charge with the phone off, it just flashes a bit....and it just keeps doing that over and over for a while and then stops. Also, not sure if it should work, but I cant get the phone into the bootloader with the battery in or out. Not sure if that should work with a dead battery though.

The phones old anyway so I'm basically guessing that the battery just got fully discharged and is probably ruined now...but I figured id ask here to see if there was something I could do to bring it back.