no hard drive installed
I have a Mac Book Pro model A1278 that was given to me. There is no hard drive installed. There are signs that there was some moisture on the motherboard and I used a stiff brush to remove that. The battery is working and when I power it up it comes on and you can hear the CD drive spin up and after about a minute the screen shows a flashing "?" in the center so I'm assuming the motherboard is OK and it's looking for the HD. Since it was given to me and not knowing the history of it should I buy a hard drive and a copy of Mac OS X and hope it works or just junk it?
Of course you just don't know what damage the water may have done. The cheapest route would be to get an original system installation disk from Apple, $16 plus shipping. To get it just call them up and give them the serial number. Next see if it will boot from the disk. If so, next try running the Apple Hardware test by starting up holding down the "D" key. See if all is working this way first. If so, now get a hard drive, format it and install a system.