Like i said guys..

The installer files are corrupted or something.. I went through updating 5.50 GEN on my PSP that's running 5.00 M33-6 3 times and they all ended up bricking my PSP. Those files came from 3 different sources as well..

Until i found a fourth one that looked promising and it worked for me.. Either that, or use XGEN Updater by Yoshihiro. You can flash straight to 5.50 GEN B with that..