If I had to guess what happened, probably they used a non hardened
screw and it couldn’t take the force involved.
For repairing, remove the broken screw (Either by punching it out if
it is not screwed in where it passes trough an item, or drill a hole
in the center of the bolt and use a screw remover (Available at most
larger hardware stores or a auto parts store) to unscrew the broken
bolt. Replace the bolt with a new one preferably a grade 5 or grade 8
If you can’t get the bolt out remove the 2 parts and take them to a
machine shop and they can do the repair for you. If you can’t find a
local machine shop to do it try a service station, automobile
mechanics are used to dealing with broken bolts.
That being said, I am sure you will shortly receive many replies
about the low quality of many of these clones. You may well fix this
and something else will quickly break. Then again it may not, only
you can decide if it will be a money pit or not.