I have netinstall repeatedly with routerOS various versions.Try to reinstall through NetInstall again.
Regards.
Hii Mr vadimbnLook at capacitors in the PSU of this router.
Please see this theme - viewtopic.php?f=3&t=119728
Try upgrading the bootloader via Bios: https://i.mt.lv/routerboard/files/p2020_3.24.fwf trying netinstall for 6.38.7 again.