Sooner or later your vita will run out of battery. If you do not have any other ideas and are ready to take risky actions (brick your vita) here is my idea. Just try enter recovery mode of the system and if that is successful try to go back to restore the system. But please, have this as a last, last, last possible solution to try. Neither I know that in your case the vita will manage to boot in recovery mode, nether that restoring system will succeed. Maybe there is a possibility to brick your device, so please, let more opinions to be shared here. Maybe a better solution will pop up. Good luck