Default [Q] Partition table doesn't excist

I have a galaxy s5 sm-g900s and have some troubles.
In bootloader when i want flashing trwp it's says: partition table doesn't excist.
At the same time recovery gives fault notices.
It seems that the people we bought it from have messed things up.
I tryed the xda solution for fixing partition table, but it hung at the last command line ädb shell 0777 /. Said file doesn't excist.
can someone help me.