eken m001 will not run from battrie

hello looking for some help please .
i have got a eken m001 that works great . the probblem is it will not run off the battrie .
if i plug in charger it shows battrie charging . and after 1hr or so it shows battrie full and lights change colour .. but when i unplug from mains supply . the eken will not turn on and run from battrie power ..

help please ...

 

Return for warranty replacement.

 

i bought it secondhand do not know were to send to
bought it from ebay..
seller said the batrrie was working ok when he sent it to me ?

 

were would i send it to ...
ebay seller said he got it from a computer fair ...
and no longer has recipt for it ..