Good news, went through the erase and upload technique and am now on current code. Apparently for some reason things got locked up and wouldn't do the upgrade with that alpha version of code. All good now. I did go through the levels of updates one at a time just to verify that the system is working as expected. Went to 1.19.2, then to 1.20 and finally to 1.21RC4 all without any further trouble.
just an addition to this but it was completely worth the bit of pain working through this, the new code is substantially more user friendly and several items i'd been fussing with are resolved now.
