Just throw them away. The problem is the processing power. Apps nowadays are much bigger than apps when android started.... way bigger.

The practice of returning old one is just to make sure the technician is really replacing the old one but at the end the one become pile of junks, same like analog phones in TM.

When I went to TM last time, they cannot even state the specification of the box. The guy agreed that for the same price you can buy 3rd party box with much better performance. So, I just get it online.