Old Congo problems

I am trying to restore an old (probably one of the first) Congo after the motherboard battery expired. With advice from Tech support I have replaced the battery and re-imaged the hard disk but it still refuses to boot up beyond the ETC Congo screen. I have also re-set the bios configuration to that supplied by ETC.  As much as I would like a trip to ETC London I am trying to avoid spending too much on it, also, my wife is getting quite used to it sitting on the dining room table!

Any suggestions welcome,