what is my car doing!!?? struggling to start then cuts out.

[lisamiller]

Hi there. I washed my car earlier (megane 1.9 dci) with fairy liquid and water including under the bonnet as wanted to remove oil from an oil leak due to incorrectly fitted oil filter. Now my car wont start!!! It tries turning over then just crunches (alternator) sounds nasty. Managed to get it to fire a couple of times and it will run for a few mins then cut out. What could this be? Im supposed to b selling the car tomorrow! Need it running so will have to call garage in the morning but does anyone have any ideas on what/ why and rough price to put right? If not will sadly have to go as spares or repairs.