I would be very wary of actually excavating alien technology until it has been studied for a very long time remotely. We have no idea of what level of technology the aliens actually had (or worse yet, have; they might still be in the neighbourhood) and playing around with stuff you don't understand the principles of could be extremely bad for your health.
As an example, imagine Victorian British engineers came across a nuclear reactor. They have no concept of radioactivity or nuclear fission, so when they decide to strip it down to examine the parts, or pull the cadmium control rods from the core for examination because they are the easiest part to get to, extreme mayhem will ensue.
The alien artifacts might be carriers of nanotechnology, spores of some form of life, the equivalent of DNA, mind altering algorithms or something even stranger.
Step one would be to build a control station on one opt the Martian moons, and set up a system of relay satellites, so remote investigation can be conducted with minimum light speed lag. Once that is done, spend a great deal of time staring at the find using multispectral sensors in orbit. Look at the find from as many angles as possible, by day and by night, and over a sufficient timespan that we know the item(s) don't become active at night or when the Martian seasons change. After than, send remote landers. The can gradually close in and begin scanning with passive and active sensors. The investigation is continually recorded in HD, so any event can be replayed and studied from multiple angles to ensure no mistakes are made, or if they are made, they are not repeated.
Finally, after all this is done, then you can start to move up to physically "touch" the items with the remote tools to take samples and so on. A robot lab can be sent down to do detailed testing if needed, but the humans always remain in space until there is enough evidence that the artifacts are inert and safe. Even then, caution is needed for the human investigators, and they may end up being exiled on Mars for the rest of their lives.