Bootloop and no way to enter in recovery or download mode

Hi guys! Yesterday I decided to unlock the bootloader, flash recovery (twrp 2.8.6) and the cyanogen 11 nightly. Everything went good until I tried to install the gapps, I noticed that the physical shortcut to enter in recovery (after the turning off, of course) didn't worked: the phone restarted or boot up the rom, but I was able to enter in recovery from the advanced restart menu from the rom. Going into the info of the phone where it says kernel there was written "unknown" and no way to overclock. So I decided to reinstall the kernel (the cyanogen11extended) from twrp, everything went good except that I couldn't restart into recovery, it stuck on rebooting until shutdown. So I tought let's use fastboot to erase ad flash the recovery partition and the kernel, but it didn't do anything even if on the cmd said okey and finished in something about a second, but when i tried to enter in recovery I always get stucked on rebooting. So I tought"well if I have the system image I could flash it with fastboot and restore the stock kernel", so I erased the system partition and tried to flash the system.img and I get the message that it is too big for the destination device. Now I don't have a system installed tye hotkeys don't work and I'm stuck on LG screen logo.
There is a solution or do you suggest to send the device in warranty, instead?