How to hard reset "Just Systems" Smile Semi Tablet?

Hi there,

someone has given me a Smile Semi (Brand: Just Systems) Android tablet.

It can power on, but it freezes during boot. It only shows the Android logo and stops.

Does anyone know how to hard reset it?

I can't seem to find any info on this tablet, I can't find the pdf manual, I can't find the distributor number too.