I plugged this in and it seems to work as it should- the display screen did not seem as bright as i would expect- but still certainly visible and functional- perhaps there is a brightness control I am not aware of. I didn't leave this plugged in long enough to charge batteries- due to age I'd assume the batteries need to be replaced- batteries are available for this on eBay and generally sell for about $30.00
This is an older tool no doubt but still does the job in the ever-growing complicated automotive world! See photos as part of the description please.