Help. I have just done an oil change on my 2006 400h car. Now the engine is dead. If I’m lucky the engine light will come on and you can hear the fan turning but nothing as in starting. No power for lights or radio. Just fan turning. I have no idea why this is happening. Has anyone else had this. Should say the engine light is an amber light. Please help. I’m a noob

 

I have just done an oil change.

YOU did it or someone else did it for you?
There is no physical way oil change will kill engine somehow. There really is not even a way to knock off a sensor or a switch during this process as the only thing done under the hood is oil cap. Unless someone disconnected battery for some reason and then reconnected it wrong. Who knows if it went into oil places.
Otherwise, if only oil pan plug was removed and reinstalled, only oil cap removed and reinstalled and engine is full of oil the way it should be ( I once forgot to install drain plug and poured oil straight down on the tarmac) - there is no way oil change can cause catastrophic no start situation.
Hence, unfortunately, it's a one of them weird coincidences that happened.
Did you try to jump stoat the vehicle? Dirty battery terminals come to mind first.

 

I have got it all started now. Unfortunately I did disconnect the battery. Now I have a warning message ,CHECK HYBRID SYSTEM’ this is not good. Wish I had took it to a garage to change the oil. I am hoping this is to do with the battery or an ECU reset will clear it. At is running wonderfully before and sounds great now. Just this message. Scared to drive it now.

 

Well...

This is why I keep preaching - DO NOT DISCONNECT 12V ON HYBRIDS.
There was no need to do so for oil change, you know.
here's what you do.
1. always post hybrid questions in hybrid section
2. go to your car and do 3 consecutive complete Start/Shut down cycles. This is Toyota recommendation for situations like this, when 12V had to be disconnected. Normally, it works.
I spent enough time in hybrid forums and owned 2 hybrids, still own one, to know better than to disconnect 12V without any good reason and if I have to - I keep back up 12V supplied to the cables.
No, you are NOT better off taking your car to an oil place. It is always better to DIY anything possible, just be careful.