The problem with pile 'em high and sell 'em cheap stuff is support that's minimal or completely absent. You MIGHT get somewhere asking Aldi customer service but I doubt it.
If you're a bit techie it might be possible to replace the battery cells but that's a bit specialised.
Your best path is probably to buy a new one.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix d.i.y tools.