I have a CTL J2/J4 ARM Chromebook. The guide for PMOS tells me to press Ctrl-U upon hitting the “OS Verification is off” screen, AKA the developer mode screen, and when I do, the screen flashes and the Chromebook beeps. Ctrl-L also doesn’t work. When I try to go into the recovery screen, nothing happens when I put in the USB. I have enabled dev USB booting too. Please help.