How to stop boot in SRM ??

Hi all !

I've put some nice flags in SRM environment to make my alpha 2100 boot 
automatically...
It works so well that now I can't stop it to get the SRM console anymore !!!!

Is there a special key for stopping the booting process in SRM console ?
Or how can I do it with aboot ?
I can't access to the /proc/srm_env... etc to reset those flags :-(

Thanks for helping me,  Pierre.