My brother had an Aptiva, many years ago. It came with warp 3 installed, along with DOS 7.0 and Win 3.1. OS/2 worked well, and eCS 1.0 also worked well, before it became unusable for modern browsers (not enough memory). The other "problem" was that it had an IBM sound card that required a very hard to find driver. We eventually scrapped that (not as easy as it sounds), and put in an old SoundBlaster.
All of that may, or may not, apply to what you have. What, EXACTLY is it that you have? Knowing the Machine type, and model, might help to answer your question (ISTR that there are probably about 100 Aptiva models, covering about 20 years).
Sell it? You would be lucky to get $10 for an old machine, no matter what OS is installed. If it is not working, you would need to describe, exactly what is not working, to decide whether it can be fixed. Putting any money into it would not be cost effective.
I hear the Aptivas can run OS/2 natively
That statement could be misinterpreted, so I will counter with this statement: " Most computers, made after 1987 will run OS/2, or eCS, natively. Some do it better than others, and the main "problems" are caused by cheap, "windows only" devices, that won't work without a specific windows driver. Fortunately, most of them seem to have gone out of business, simply because Linux has become big enough to get the attention of the manufacturers. The other major "problem" is lack of drivers for the newest hardware, which would not be a problem, in this case.