Well, I made it myself! Looked and looked around the web and finally understood that what was happening is well known as a “bootloop”, and after more looking and reading I understood that I had to reinstall (and how to) the firmware from the SD-card. The only problem was that I had no SD-micro adapter. Bought that today and everything worked out. The phone is now fine, and that is great, because yesterday I was prepared to throw the phone in the bin and buy a new one... Pretty panicked huh?
If of interest, this was the pages I found most help:
[DroidX] RoOoLeR's Guide ROOT / UNROOT / BACKUP / ROM / SBF / OVERCLOCK
Ultimate Guide to the Huawei U8800 - Android @ MoDaCo
Huawei Firmware U8800 - MoDaCo