I think I had the same problem. Phone just kept rebooting after ubuntu installer flashed the recovery. I solved reflashing TWRP and then I cleared system, data and cache. After this procedure, the phone never rebooted again.
I think I had the same problem. Phone just kept rebooting after ubuntu installer flashed the recovery. I solved reflashing TWRP and then I cleared system, data and cache. After this procedure, the phone never rebooted again.