MTH Climax with 5 volt boards non operative.

I would try replacing the BCR with  know good battery. However Do you hear anything at all? slight click?   Try deleting from the remote and adding again. What happens in conventional? same thing?

No clicks at all. I run conventionally. Why should a battery be better than the BCR?

The BCR is a good item.  I have many engines and I run a battery in all of them.  I keep a record of battery replacement on my workbench computer.  When they get old, I throw them out and put in new ones.  They all get run and stay charged.   Would you run a battery over 5 years old in your car or home smoke detector.

If you do run a battery, do it right and buy a new one from MTH.  Stay clear of great deals at tool warehouses or Radio Shack.    I do not care about the great price deal or the ratings these bargain basement batteries boast.  You get what you pay for.  

If you run conventionally, whether a battery or not, the engine should click and start up.  If it does not, the board probably has failed.  This is a tight engine, and the only replacement that will fit is a PS-2 3V board.  With small speaker.  Needs to go to a tech to test/repair.  I can do this if needed.  E-mail in profile.  G