There is a bus service between Arinsal and Andorra La Vella, passing through La Massana. It is not very regular so it is worth checking the timetable before planning any trips. The cost is reasonable.
The road continues up out of the village and stops about another 1 or 2 up at another hotel. Then there is a semi-private road that winds up the mountain for about 3 or 4 miles to the top station of the cable car lift.