@Nerox
It's a little concerning that you've not been able to connect it in Mass Storage Mode after loading Cure firmware. However, it has the ability to reach preboot so there's still hope. Are you sure that you made the Cure3 fw properly? Even tho' QuickCure also didn't work that's not conclusive because QC doesn't work to restore MSM for all bricked devices, only for most. If you made Cure3 fw just once then do it again from scratch or try flashing [Only registered and activated users can see links. ] that i just made.
Spoiler: Decryption Key if Needed
ID4SpNwtjlizr-GRSNqytIz5cuqo1lKvNJwhRg-AQME