Hi,
My phone's compass doesn't working ...
I've read that I need to disable the PTT to fix this issue!
But this advice was for the 5500pro ...
What can I do ?

Hi there! First thing to do is performing a factory reset from the recovery menu, as showed here:
http://bbs.blackview.hk/viewtopic.php?f=192&t=334922

If this can't solve your issue, that mean that your gps module is faulty. In this case you'll have to contact your seller to have your phone repaired\replaced under warranty.