colzilla, I wonder if you can elaborate on your solution above as I'm a bit stuck. Long story short, I dropped my Hudl and now it keeps asking for my Google credentials before rebooting ad infinitum. Googling the issue brought me here. I've tried flashing the Helios ROM and the stock images from here, but each time I get the IDB fail error indicating that it's bricked. I can get it into ROM MASK MODE using rkflashtool in Linux (Mint, Kali & Debian tried so far) and then I run the upgrade_tool, but when I go back to my PC I have to switch the Hudl back into flash mode and get the IDB Fail issue again. Any chance you can give a more detailed walkthrough before I defenestrate my Hudl permanently?