So, today I almost died of heart attack when my iPhone got stuck after removing a theme from Cydia.
It wouldn't turn off, go to the home screen, nothing! It was just frozen and wouldn't do a thing.
If your iDevice got frozen on any Cydia activity, such as removing something or so, press the home button + lock button until Apple logo shows up.
Then just wait for it to restart. Note: This may take some time, be patient.
After it has restarted, Cydia will be in Safe Mode. To go back to the normal mode and reactivate all your JB apps, tap in the upper middle (where usually is the clock) and then tap Restart.
Like this your Cydia apps will be running again.
Warning: After the SpringBoard craches, Cydia icon may disappear and still tells you it's installed. If this happens to you, restore your iDevice and jailbreak it again.
I hope this helped you.
