Looking at the provided picture, I believe that the display in the Barcrest box is saying "t0.6" which should be Top Dollar software version 0.6.
That is not an error.Also based on the photo, the main part of the S+ machine is not booting (no displays on the reel glass). As such, the Barcrest box won't advance past the t0.6 message until it's communicating with the bottom machine.
The issue with the S+ machine could be as simple as the power supply connector that generally causes issues:
https://newlifegames.com/nlg/index.php?topic=28443.0Of course, it could be a bigger issue too, but there's not enough information here to determine the issue. As far as price, it depends on location, but Top Dollar machines have been fetching, pardon the pun, top dollar. It will obviously be worth more if it's all working.