The problem wasn't upon rebooting.
The problem came upon when romtoolbox edited your system to theme specific files.
Sometimes things go wrong when editing system files. Now from what you're saying, that your device keeps rebooting over and over again. This is called a "bootloop".
Possible ways to fix this issue.
(If you have a custom recovery installed)
1. Wipe Data, Cache and Dalvik Cache. Then reboot device. If no luck then...
2. Download a ROM for your device, send it to your device, wipe Data and Cache, flash the .zip and reboot. If no luck then.
1. Download the official update for your device, most device companies usually provide stock images for their devices. Follow their instructions and you should be good to go.
That's all I got.