Installing Plugin brought down Matomo on premise


I am website owner and a noob when it comes to coding. We have been running Matomo on premise for months for our website. Today one of my team members was trying to install the ‘Tag manager Extented’ plugin from market place and the walls came crashing.

Now we are unable to login to matomo please find the error message below.

Our whole tracking is on standstill and if we have to reinstall matomo we might lose months of data which we cannot afford to. Can some one please guide as to how we can resolve this issue ASAP? We have a lot at stake here.

Thanking you in anticipation.