Bootloop after flashing TWRP (Also lost recovery)
Same problem with my BQ M8... 
Here is how I solved it:

-With the phone conected via USB, Launch CMD to run ADB and test as many times as needed that the PC and terminal can talk to each other with the command "adb devices". Eventually after several attempts, it will return the device and number. Posibly stating the work "recovery".

-Go into bootloader with the command "adb reboot bootloader". As before, try it as many times as needed util it works (that means you will have to re-Run the ADB, and un-plug, plug the phone).
-Once on Bootloader (you can verify because the phone screen is in "Fastboot..." state, you have to Launch in your PC the FLASH TOOLS (hpoe you know how to use it)
-In FlashTools select only BOOT and RECOVERY tickmarks, and leave the rest unmarked). Then Press on the DOWNLOAD green arrow
-Now back in ADB window, use the command "fastboot reboot". This will re-start the phone, and FlashTolls will immediately kick in, Flashing the BOOT and RECOVERY files back in your phone (it takes miliseconds).
-The phone will re-start and this time you will have all in STOCK (you´ll also have Bootloader Locked again).

Hope this will help you out.