Hi
The hint with loose connections is right, bad solderjoints are often found in these mashines too.
For me the display shows the typical symptoms of uPC controller is not workink proper.
Often this is caused by bad capacitators specially C35 10uF at the 5 Volt regulator 6IC4.
If you are handy with a soldering iron and have at least some basic electronic skills you could solder a new one in.
Before you are opening and working on the Beomaster always pull the mains plug from your AC outlet!
As you are working on the 5 Volt line for the uPC always think about ESD!
The cap is mounted to the legs of 6IC4, right side of unit on the heatsink mounted to the chassis, and easily to renew.
Next would be not as easy to acsess:
9C85 22uF this one is also a filtering cap for 5Volt line in the uPC housing can.
Kind regards
Christian