1. You have to get your ps3 into factory settings just like when you downgraded

2. Now just like you did for downgrading you do it for update so turn off the ps3

3. Get a usb and in the root put the level2 dialog file 1 and then the update to 3.50 ofw.

4. Connect the usb to the ps3 and turn it on just like in the downgrade
5. These process is automatic so in a couple of minutes your ps3 will shut down.

6. Once the ps3 is off take the usb out and make sure that the ps3 has updated to 3.50 ofw and then turn it off.

7. Then on the usb delete all thew files and then proceed to copy and paste the level2 dialog file 2 to get your ps3 out of the factory setting.

8. Once again just like in the downgrade connect the usb to the ps3 and then turn it on and the ps3 will automatically turn off.

9. Turn on your ps3 and you should be at 3.50 ofw.

10. From there you should be able to update to 3.55ofw and once there you can update freely to 3.55 ofw.