Here's what I know.
If you tried to install uberkernel without being on build 3171, it will start a boot loop cycle that only a doctor can fix.
Even if the install actually fails. Using recovery kernel does not help. Only a docotr.
Happened with my UK Pre3.
In fact, given that all kernels and homebrew will be based upon the EU doctor, I doubt you have any choice left other than converting your ATT Pre3 to EU.