second HDD not detectable after change of magsafe board?!

Hi,

I had my MacBook Pro (Early 2011) at an Apple store because my MagSafe Board needed replacement (all hardware tests were ok but the magsafe board). I picked it up and realised at home - I don't see the second hard drive anymore (I used Disk utility which only showed my SDD, PRAM reset didn't help). Any ideas to resolve this? Thanks!