OK, SOLVED, thank you all for your input...
How..? looked at more ebay listings (searched "M328 tester") and found the answer... AA size 3.7v Battery 14500 - not very common size (imagine putting one or 4/6 of these, by mistake, in place of 1.5/1.2v AAs...!)..
Since I don't have one, I've tried with an external, more standard, 18650. I "activated" the battery (shorted two pins as per instructions from yet a diff ebay seller) and all is good!!
Cute little device, seems to work well, uses SMD 328 but there's no ISP connections.. looks real pretty next to my Quad DSO and Arduino bits and pieces.. Happy!
Grazie, ciao
Luigi M