In my experience to get at the innards of a flat panel, start by removing the stand. There may be some additional screws but the case is usually held together with internal clips around the edge of the bezel -- look for small slits in the join between back and front panel and insert a slim screwdriver to release the clips.
Thank you for your reply.
Yes it is well out of warranty: it has been standing here for about a year after it started sparking and smoking... but at the time replacing it was more urgent than the attempt of repairing.
I had tried all the standard ways to no avail. Meanwhile I've learned, you have to take down the rim in the front to get at the clips from the back panel.
The cause of the sparks was a loose connection, that is remedied meanwhile.