Temp gauge climbs to Hot as soon as I turn the key on.Thermostat new, same issue

What is your question?

01 BMW 528i, thermostat replaced. It starts at once but after 5 mns acts erratically, engine runs fast but water in the radiator is normal. If turn off, it becomes hard to start untill cool off. Thanks for your help.

How long has your 2008 BMW 528xi had this problem?

Yesterday