Files for Sony's DPT-RP1
You should probably skip this at first, but if flashing system doesn't fix the problem, wipe data and then flash system again.
To wipe data, boot into diag mode and run /usr/local/bin/factory_reset.sh. That should wipe data as well as mmcblk0p16, which means you'll have to copy the img file(s) back onto the device.
Download system.img from the 1.4.01.16100 Stock folder. Check that its MD5 is 5081ec24954714373229a7c76154509a.
Boot your device into diagnostic mode. Open a terminal connection and run /usr/local/bin/mass_storage. It will mount its storage partition (mmcblk0p16) as a USB mass storage device on your PC.
Copy system.img to it, then safely remove it.
Go back to the terminal, hit Ctrl+C to end mass_storage and it will unmount from your PC if you haven't safely ejected it.
mount /dev/mmcblk0p16 /mnt/sd
cd /mnt/sd
md5sum system.img
Check that against the above MD5sum. If it doesn't match, start over and DO NOT FLASH IT.
Run extract_sparse_file /mnt/sd/system.img /dev/mmcblk0p9. It won't output anything until it's done flashing, so don't touch the DPT, don't touch the PC, don't move the USB cable, don't cancel it just let it finish.
Once it's done you can type
umount /dev/mmcblk0p16
reboot
and it should reboot into a stock system.
You probably do NOT need to do this. Only do this if your device never makes it to the welcome screen.
I haven't corrupted my boot partition so haven't had to flash it yet. But if flashing system doesn't work and you're still able to boot into diag mode, you can try flashing the boot partition.
Follow the same instructions to download boot.img, copy to the device, and check its MD5. Note that boot.img's MD5 should be 6a83136b15ad2a55f3e0240a0fe9c1a7.
If it matches, run dd if=/mnt/sd/boot.img of=/dev/mmcblk0p8 bs=4M, then unmount and reboot.