Yes putting the lv2diag.self and the 3.55 OFW won't do anything if your PS2 won't go into FSM
After you started up with Downgrade dongle I didn't notice you hit POWER then EJECT very quickly
Do you have the switches set 1-5 down, and 6 up? At 1:04 in the video.
As I don't know what tutorial you are following here is exact steps:
1. Put the e3_downgrade.bin file on your sd card. Insert sd back into flasher.
2. Set switches 1 - 5 down and 6 up.
3. Press reset, then start. Wait for the blue lights again. When done lights alternate blink.
4. Shut down PS3 from XMB.
5. Power on PS3. You should get a screen that says "Plug in controller to USB and press PS button"
6. DO NOT DO WHAT THE SCREEN SAYS!
7. TURN OFF POWER BY SWITCH OR PULL POWER CABLE.
8. Insert your downgrade dongle in the right USB port.
9. Plug in power cable or switch back on.
10. Press POWER then EJECT in that order within a split second. and wait for the PS3 to shut off by itself.
11. Place the Lv2diag.self and Rogero_v3_with spoof from the step 1 folder onto a USB Flash drive and rename R_CFW_v3.1_PS3UPDAT.PUP to PS3UPDAT.PUP.
12. Replace the downgrade dongle with the flash drive in the farthest right USB port.
13. Turn on your PS3. Wait. In about 3-5 minutes your PS3 will shut off.
14. Take the flash drive back to the computer and quick format to fat32.
15. Place the Lv2diag.self from the step 2 folder onto the flash drive.
16. Put the flash drive back into the farthest right port of the PS3, turn on and wait, in about 30 - 45 seconds it will shut down again.
17. Take out the flash drive, then turn on your PS3. The first thing you will see is Rogero when your PS3 boots up.
18. Now you need to repeat Chapter 1 Part 2 Make some bios backups. This is IMPORTANT in case you brick while installing other firmwares.