Hi @rei_vilo Thanks for the reply. After I had made the above post, I went back and flashed the cc3000 and the tinker on the second core that I was also having the problem on. That went very well and the unit is now working fine.
Not sure which core I had a problem with late yesterday but I had attached a jumper in the wrong place drawing a lot of current through the regulator. This is maybe a real stretch but I am wondering if a core that might be damaged in this way could cause my AP to get in a latched up state causing difficulties with a second core.
There is a lot of IFs here but am just trying to put all the facts together for a clear picture of the situation.