Whether He damaged the GRUB DeepinOr boot, you will have to use repair tools.
First you have to Deepin RecoveryWhich will allow you to access a kind of "emergency mode". The tools to solve the boot is Deepin Repair.
If you can not install because it only displays text error will have to use
fdisk. First find the partition which is starting with the command
sudo fdisk -l for quick route. Y
sudo blkid for UUID. Finally restart your computer and go to advanced settings and select fsck.