Can not turn on or charge, battery with yellow triangle

So we've got an s5, completely dead, and when we try to plug it in it gives a battery with a line through it And a yellow triangle.

We've replaced the battery, cleaned and checked all contacts, and replaced the charging port. It still gives the same issue. Any help would be great

EDIT:

It WILL boot into recovery mode, hoping for an option other than attempting a factory reset

Download mode shows that KNOX is not tripped, not sure if that matters other than it not being rooted