check the level of the fluid in the gearbox.
You should go a good workshop and have the starting clutch calibration done (specially if you or your mechanic disconnected the battery anytime recently)
the D blinking is a sign of error in the controlling of the gearbox, if you connect a scan tool it will tell you the error, it maybe a simple speed sensor fault only - but you need a scan to get that correct.
The speed sensors are hall effect sensors - not too hard to test for a good technician.