Check my new post you are ok as 3.50 will work I just use 3.41 as I have it on my HDD. So you can still do this.
1- Make sure your PS3 came with at least 3.50 OFW if not just stop or you brick as one can't go lower then what came from the factory.
2- Dump NOR flash and ensure you have a valid dump before writing anything or you will not have a way to recover.
3- Downgrade to Rogero 3.55 v3.1 w/ 4.11 Spoof install with freshly formatted FAT32 drive every time you switch FW's
4- QA flag your system, use
Rebug QA token activation tool and set "Advanced" this is important not the normal one
5- Move the cursor select “Network Setting“ press the following button combo with your PS3 controller: L2 + L1 + R1 + R2 + L3 + D-pad Down
6- You are now QA flagged, enter recovery mode and install a OFW 3.50 or lower
7- Once on 3.50 OFW or whatever one can then simply update to Cobra 3.55 in recovery mode
If you follow those exact steps you will not brick and be using Cobra in no time. BTW if you have your old dongle PM me I might be able to help you recover as I bricked mine during one of the 4.XX updates but I am back on 5.0 and working great.
Some things that might help
E3 NOR Dump Checker v1.0Minimal FW CheckerRogero 3.55 CFW w/ 4.00 Spoof3.50 OFW3.50 RETAIL/CEX | MD5::0215e26d1dadeb950471a9c3397a140a | SHA1::b819861f75d50882142cbec8af54b00012bc049dCobra NFW Rehosted by me as Bubba lost it in the crash of MU
Also please leave rep if you feel I helped so simplified the instructions. I made a post asking for help yesterday and now it is removed and I have no idea why other then I may have pissed off a mod by reping him badly for a sad remark made to someone asking a question and gave a piss poor answer that wasn't correct or even close.