Welcome to Beoworld !
The "P" does not mean anything specific but it reveals that the processor is not running
its programme as intended.
The main issues of the Beomaster 6000 are aging capacitors and cracked solder joints.
Caps generally, solder joints at the lower edge of the processor module and
at the board right below the processor board. Mainly where connectors are soldered in.
The processor reset circuit can also act up.
Will it go into standby (red dot) and in the given case is the red dot the only thing lit then ?
Any reaction to the remote control (if that option is fitted) ?
Martin