Could anyone give me an idea what may be wrong? I can no longer get any display at all. No check engine, error codes, or anything. Everything else seems OK? Any advice would be appreciated.

there's 2 reasons for this to happen.
1. you might have to change the entire cluster due to the car being overused.
2. there might be a loose connection

these are rare but common faults in 5 series

i advise you check the wiring on any parts you or somebody else was recently correcting

hope this helps