I've tried a few methods of getting recovery back but so far have failed. I always end up with that droid and a red warning triangle, which if left long enough it will boot into android on its own.. Any help would be greatly appreciated.
I'm actually having this issue as well, I'm curious what you did to solve it?
I flash twrp with fastboot and get the red triangle when I attempt to boot into recovery. However from fastboot if I do the boot recovery.img command, twrp will boot up and run fine, but I cannot boot back into recovery straight from the bootloader, without booting from fastboot.
I'm not sure what the true issue was in my case. I downloaded another copy of twrp, flashed it and everything worked out. Bad cable or corrupt file maybe. I'm not sure.