@Constantinnn
Welcome to GPS Power.

It's 'bricked' and from the circumstance you described it's either hard or soft bricked. it's probably only 'soft-bricked' however it may be a hardware failure such as the flash chip has malfunctioned.

If it's soft-bricked, in all likelihood it's only a corrupt file causing the problem that prevents it from booting up, probably a map IMG or a GPI (POI) file. Read the initial post of this thread again, you'll see links to [Only registered and activated users can see links. ] and [Only registered and activated users can see links. ] and other threads you might need. Post again if you have further queries.