I’ve checked the boot light and that is off. Not sure what to do now.
What did you do to charge the battery after Mazda assistance visited.
If this was my car I would disconnect one of the battery terminals and connect a multi-meter between the battery and the disconnected cable. Set to Current ( amps), most MM have a 10A fused circuit. I would maybe put an additional inline fuse in the circuit , (easilly accomplished using a blade fuse, two bits of wire and two female spade connectors).
I would then check to see what the parasitic current drain is with the IGN off.
You could then pull fuses to see which circuit is possibly draining the battery.
If there is no significant current drain then the battery would be my prime suspect.
Edited to add link:
As it is so ‘new’ to you I would contact the selling dealer ASAP and ask them to solve the issue. If you purchased it privately it will still be under warranty so the same advice would apply.
I hope this hiccup does not spoil your enjoyment of your new car.
Begs a question of at any time in it’s being born into a Life in Covid the battery was allowed to drop to dead…in which case…
Agree with that entirely.
Same problem on my Volvo I bought.
Laid up for 6-8 months.
It would charge, but not fully etc etc.
Needed a new battery. 
The assistance guy sorted it. I assumed he charged the battery, but was quite quick.
What would that mean? Does it mean the battery would need changing?
That’s all too complicated for me I’m afraid. I’m an old lady 
Yes, I plan to contact Mazda assistance again tomorrow and will ask them to take it to the nearest Mazda dealers for repair. I just feel so fed up and disappointed.
Ok,
I’m only saying it’s one possibility to be eliminated by knowledge based testing.
I know it sounds odd ( and it is) but if ( big if) the battery was ever allowed to go below a certain point, or even totally flat, they tend not ever to recover fully no matter how charged by various methods.
I’ve had both experiences over the years…insofar some recovered sufficiently, some did not.
You either have some sort of " electrical parasite issue" draining it…or the battery is a goner which should not be your issue at all. The thing is still new and you have not gone any place with it…yet.
Do not despair…it just needs a bit of corrective TLC and you will be fine again.
Last from me.
Do not leave it too long between usage and if you go on holiday say…try and put the battery on a trickle.conditioner charge in future. These cars are designed & engineered to be used and driven with lots of gusto. They love it.
Thanks ever for much for your reply. I’m only feeling despair because it was so amazing to get this beautiful car, then to have nothing but trouble. You’re right though, it’s all sortable and I need to give my head a slap 
Just another note that is important if your car as the i-loop/stop start system. If it has it will have a very specific battery that requires a special charger to recharge correctly when it has been fully discharged. Mazda main dealers will have this equipment.
If you need a new battery it is worth taking a photo of your current battery and making sure it is replaced with the correct ‘special’ battery.
I do feel for you but as you have recognised this can be fixed so try and keep those positive thoughts alive.
Yeah just getting it started on the roadside and you going for drive most likely isn’t enough to recharge your battery fully.See if you can borrow a charger or take it back to garage for them to fully charge or replace battery…I wouldn’t worry about battery drain until your confident the battery can be ruled out. Most likely been sat unused before you took delivery same happened to my main car when bought from dealers in the middle of lockdown.
Thanks for your reply. I’ll contact Mazda assistance tomorrow and hopefully they will take the car to the garage.
Love the big pooch by the way.
Mum’s boy/girl I presume!
Batteries sold by retailers may be sat but they are sat charged. Modern batteries fail if they fall below 10volts due to excessive sulfation on the plates in the battery.
I’m going to phone Mazda assistance this morning. Should I ask them to replace the battery?
If you explain the circumstances to them - i.e. it can’t hold a charge overnight - I think they will probably consider changing it. They will be able to test it.
Good luck. I’ve always had exemplary service from my local Mazda dealer.
If the battery is proven to be goosed I cannot see the Dealer having a leg to stand on not to change it out HOWEVER it’s important it is changed for a pukka original in my opinion and not s spurious budget job. Its a new car pretty much.
I don’t see a big issue coming really. Some Mazda dealers have had bad press but there are decent ones out there too.