Welcome to Beoworld, we are pleased to have you as a new member.
I am assuming from your comments that you swapped the battery from one of your working Beocom 6000's ? Please confirm.
Assuming that the battery has been swapped, then to move forward I need to know what version Beocom 6000 you have, either a Mark I or Mark II
A Mark I has a DOT on the button at the 9 o'clock position of the centre dial and a Mark II has the letters INT in that position, which is yours ?