Simply put:
If your sysnand is updated to 10.4:
- You are out of luck, you can't access Homebrew or CFW anymore, to bad
- No you can't downgrade from 10.4
- If you don't have a hardmod AND a 9.2 or lower NAND backup (always the frist thing you should do when downgrading) you are out of luck
- If you lose your HD with NAND/EmuNAND backups, you should have done a NAND backup again (You all knew 10.4 was comming very soon)
- Again: No you can't put any NAND backup back without a hardmod if you are on 10.4
Conclusion:
- Always make a NAND and EmuNAND on a regular base!
- Get your systems hardmodded, it's worth the money if you can't do it yourself.
- If you are on 10.4, you have entered the waiting zone for a 10.4 hack (if ever)
- Block Nintendo updates in your router or remove your internet settings in sysnand (if unlinked)
- Never trust your system to someone else, you might get it returned on latest FW
- Don't put your system in sleep mode if you are in SysNAND! or EmuNAND if you didn't block Nintendo updates properly
Blame yourself for anything that happens to your system, you didn't want! Not somebody else!