My son's car batteries [original and new] have gone flat, dont know if there is an electrical fault

what year is your ka? if its the later model it has electric power steering. the warning light means a fault in the system or it needs to be recalibrated ie. if the battery has been disconneted or gone flat. try with engine running turn steering wheel from full lock to full lock both ways a couple of times if that dont work there is poss a fault in the system and needs to go to a dealer for safety reasons good luck

You can use one of the plugs that go into the power point/cigarette lighter. Cut the end off add wire to reach a good 12 volt battery. Plug it in. This should give you power to open the boot with the switch.

run the fault codes
check that the cam shaft is turning (broken timing belt)
check immobiliser for correct operation---flat fob battery

Have you checked the battery and battery cables? Your battery may have gone flat.

no vehicle id but sounds like a ford, 1st connect jump battery the battery may have died but may have gone flat trying to start,if you have power at lights etc with other batter connected listen for fuel pump buzzing it should do that when ign turned on for a few seconds, other probable cause ign coil

Maybe a bad contact of battery terminals.Remove them,use a bit if sandpaper and connect them again.
You say you have a new battery,you may have something discharging it or your alternator is ot charging you battery(common fault on these).
Dont know what engine you have ,but if its the diesel,its a common fault for the glow plug module to short circuit and flatten the battery.

check that all the vacuum lines are hooked up to the headlight assembly and relays are plugged in check for voltage at the headlight motors if none then you know its electrical

ok so looks like this one has been solved by the dealer.
I had it towed to them, and they said the battery had to be replaced (only had 8vlt in it)
and something to do with the cell inside the battery had failled. No surprise here - its the same battery which came with the car - 5 years or so ago.
They are still working on it, so wont know if its anything else. Battery's in Australia arent cheap
for this car - 125 dollars, and neither are most parts. But then i use the car for business, and drive everywhere. The car was used everyday, but i suspect it went flat, as most copen owners would know, seems to go flat if you dont use the car for some period of time, like 1 week or so,'

for your mazda problem you must to check the followings
1- chech fuel filter
2- check electric fuel pump
3- put switch on you must to hear a click if no so there no electric power on pump in this way take out electric fuel pump and tested if not work so you must to change it by new one and also you must to change the fuel filter by new one.
this is the best way for start your car and let me know if every thing ok