I believe installtointernal isn’t supported anymore in CE, maybe in LE. If you can successfully boot from SD card you should try this install on internal memory.
If not you need to unbrick the device with the shorting pins methode aka mask rom and flash an android image to have a new bootloader.
See also this: https://discourse.coreelec.org/t/bl301-injection-problems-help/6458/351?u=garcea