Frigidaire Freezer problems

I just recieved this upright freezer from my stepmom, every item inside was frozen, I’m not sure if it was running when we unplugged it. I hauled it home and let it sit overnight before plugging it in, there was no water under the freezer and no frost that was visible. I plugged it in and it has run for over 2 days , the setting is on 4 (0-8 range) and the lowest temp was 10 degrees , I changed the setting to 2 and it still ran .. I turned it off for an hour and turned it back on and it still runs. Can you help me? Thanks

how old is your freezer, is it an upright freezer or chest type freezer. is this a self defrosting freezer?
there are many answers but it depends on what type of freezer this is.

Here are your parts
Replacement parts for FRIGIDAIRE MFU20F3GW3 Frg(v2) / Upright Freezer | AppliancePartsPros.com

By the sound of it you are getting some cooling. Remove the cover in the freezer so you can inspect the evaporator coils.
If you only have frost in one area (usually where the freon enters the evaporator coils) and the compressor is running continuously then you have a sealed system problem.

There is a possibility that it is a freon leak and you are low on freon.
Also depending how it was moved you may have contaminated the system.

Here is a good link with basic fridge/freezer repair info.
http://www.applianceaid.com/refrigerator.html
Check out the example pictures part way down the page in #20.