Hello and welcome to Just Answer!
The first thing that needs to be done is check the oil pressure with a oil pressure gauge.
Most mechanics have one! It screws in where the oil pressure sensor goes, so you have to remove the sensor to install the gauge.
The minimum spec at idle in drive is 13psi, typically we see around 20-40 psi.
Then if you have oil pressure rev the engine to 2000 rpm and the spec is 37-75 and typically we see around 45-60psi.
If you have good oil pressure, the problem has to be electronic and if your oil pressure is low, let me know!
So, with the pressure gauge installed the oil pressure dropped to 0 or was he going by the gauge in the instrument cluster? I am not sure if he removed the pressure gauge and then drove it again.
Could you Try this? - Sit in the vehicle with all doors closed and starting with the key in the off position turn it to ON, OFF, ON, OFF, ON within 5 seconds and leave the key on and watch the digital odometer to see if it displays a fault code. It will be a P followed by 4 numbers example P0700. When it is done displaying codes or if there are no codes it will say done.
I would like to know if has a P0522 or P0523 fault code which are codes for your oil pressure circuit.