My renault megane scenic only starts some days and others it is completely dead, I charge up the battery and it's fine for a few days and the dies again, got a new battery and the alternater is fine.

okay , it needs service in a real shop.
what does it do now.
is the starter dead?
keep in mind we can not see the car , drive it or hear the
starter motor fail or not.

here this sound?

https://f005.backblazeb2.com/file/notstart-cranks-fast/cranks-but-not-start.mp3

The car manual will tell you how to reset the clock. Or contact the dealer OR
go to manufacturer web site for manual download.

Sounds as though there is a charging problem with the car. It starts when battery fully charged but when the charge is low it fails to start. I would get a mechanic to connect his meter to the battery and see if it is charging as it should. It is also possible that something is draining the battery when not in use. Check interior lights are going out when parked up, nothing is plugged into cigarette lighter outlets attached to sat nav etc., things like that.

Alternator problems may be. Check if that gets the charge while engine's running.

We do not have this make in the USA so have no tech info on it. Sorry.

I had my clutch replaced yesterday on my renault scenic grand and now the battery charge fault is showing on the display and the battery has completely died

The best way is to charge it the same way as any other car on the battery terminals!

Please do rate my response. Thanks!

put the red wire to the positive and the black to the negative and leave on charge for at least 2 days then it will start providing the battery is any good

if the red light flashes on the dash its going to be an immobiliser fault, normally it is the key that is at fault, the keys are pricey about £80 plus programmimg, but you can manually override the immobiliser on the early scenics, just pop into your renault dealer and ask for your immobilser code, normally charge a tenner or so, and ask if someone can show you how to put it in.

Possible accesory power relay staying on due to an internal fault. It is above the fuses in the glovebox. Try sitting in the car, locking it then giving the relay a tap