Really I cannot stress how important it is to insist that the fitter does a full water leak down test and use a torch under the dashboard to inspect for any water leaks PROPERLY. I had a poorly fitted replacement screen done badly by a so called 'professional' company. To my horror it caused many many thousands of pounds in damage and huge amount of labour and stress. You really cannot imagine.
Firstly the water leaked onto the left hand side [just a trickle] through the base of the window. This caused a short circuit of the Window/Dock Lock ECU. This then in turn caused the windows to go up/down crazy style and doors lock/unlock which then proceeded to destroy the drivers side power lock and take out the lock relay too. This happened overnight while at a swanky hotel [unfortunately we got torrential rain that night!] so I came back to find the interior soaking wet and the windows fully wound down, along with a completely flat battery!
... Also since the door lock had completely seized up the door panel had to come off to replace it, none of the usual door opening tricks worked. However the door panel couldn't completely be removed to get full access required without the whole dashboard upper and lower coming out too, including steering wheel, air bags, clocks, centre console, stereo, etc. (also required to isolate the source of the leak!).
If I had carpets/underlay [I don't] they would have needed replacing too. It also damaged the digital throttle potentiometer too. In summary the whole situation was a big headache and many many hours of labour and thousands of pounds worth of damage....
So YES... Make sure they do the job PROPERLY... This was from literally just a few drops of rain!
I learned the hard way. My car normally doesn't stay outside and since it was many months elapsed since the 'repair' of the windscreen [garaged car] there was no way to prove they where at fault.
so I had to sucker it up down to experience....
> New Power Locks
> New Window/Door Lock ECU & Relay
> New Digital Throttle Pedal
> New Carpets & Underlay [If I'd had them]
> Full dash out, airbag, steering wheel, clocks, door panels, the lot...
You get the idea...
Had it leaked on the right hand side too it would have also taken out many other ecu's too such as aircon, suspension ecu, etc but this was just from the LEFT hand side.