How to get a full backup of a hard disk from a dead MacBook? My MacBook is not booting up due to some short circuit problem.

Apple Store has promised that they can repair but there would be data loss.

I want to take out the hard disk from the MacBook and take a backup of it. Then re-attach the hard disk and give my MacBook for repairing!

So far I am unable to find any way to do a full backup of a hard drive.

I would like to get some helpful pointers.
Depending on your MacBook model, removing the hard drive may void your warranty, so it might be better to prediscuss this with the store or ask them for other options. They may also offer you a way that they can do the backup for you (at extra cost maybe) or give you the old hard disk back after getting your MacBook working again.