Transit custom 2014

[Bluebird1927]

Hi new to the group I have a 2014 transit custom went to the shop earlier and it started fine came out of the shop 10 mins llater and it wouldn't start just a click I tried tapping starter and no different I rocked van back and for and still all I got was one click noise I managed to bump the van to get it home and it drove no problems now I'm back home all I get is the click and engine won't turn over any help or ideas? I did notice the starter had oil on top from a previous oil leak. Would this cause the starter to fail?