Hi,
I tried going back to stock from CM11 today (G2 EU version), but got stuck in the boot loop.
I tried loading different firmware versions, all with same results. I cant get into recovery, only download mode.
Hold down the Volume up and Volume down for five seconds. Then Hold down the power button for 5 seconds. The phone should reboot and continue to loop. Next take the phone and toss it at a concrete wall