Look up deed info in the county registry of deeds. Cross reference this with the town tax map. There will not be exact coordinates. But you should be able to get a good idea based on roads/adjacent properties.

You can also go thru MEGIS and there are GIS property maps for most towns in Maine. They're extremely approximate in rural areas, but it will get you in the ballpark if you know the tax map & lot number.

There is the option to export the town data to Google earth which makes it fairly user friendly. From there you can export the corners of the lot to your phone. Like I mentioned about it is aprpximate and may be off by several hundred feet depending on the area. I believe it is based on tax maps which are frequently a guess, especially when they use natural landmarks as a boundary.

Google earth can also be helpful for finding old property lines as you can see the difference in tree ages. Flip thru the different image date options and one may be more helpful than others.