Mazda CX-9 Pricing and Specs

That's quite high mileage, but in a modern car with vastly better metallurgy, engineering design and oil quality (particularly multi-grade oil) it's not impossible for a car with that sort of mileage to still be in perfectly serviceable condition.

Frankly, if you're not after something newer with newer tech and convenience, and you're still happy with the Mazda, the advice is probably to keep it and drive it till it will drive no further. As it is, if it's getting close to 300,000km, it's not worth very much to trade-in or sell second-hand, so keeping it and squeezing every last kilometre out of it is the budget-conscious way to go. The exception would be if a bunch of little things all go wrong at once. At which point, you're probably wise to quit it  - even though it's worth very little - as a means of not throwing good money after bad.

In some cases, with some versions of the CX-9, you can get a long screwdriver in between the bonnet and grille and manually flip the catch that will allow the bonnet to spring open. The trick is that you have to know where the catch is and since you can't see in there, it can be very difficult if not impossible.

If you have access to one, a borescope (a tiny camera on a thin, flexible shaft, might get you to the point where you can identify the latch and successfully aim the screwdriver. But at all times, you risk damaging the grille or bonnet.

You could take the car to a Mazda dealer or specialist who has probably seen this thing before and may have a few short-cuts to get the bonnet open. And since you're going to need a new cable anyway, you're then in the right place. If the job is a really tough one, you may find you need to remove the grille and even the front bumper to gain the access you need.

If the door flies open when you unlatch it, it sounds as though the problem might be with the check-strap, rather than the hinge. The check-strap has the job of limiting the amount the door can open and avoid it flinging into whatever is parked beside you. If the actual hinge was the problem, the door would almost certainly drop when you opened it, making it very difficult to close again.

In either case, though, it should be a pretty clear case of a legitimate warranty claim, and a 2020 Mazda is still well within the factory warranty period, regardless of whether you're the original owner or not.

Take the car straight back to the dealership you bought it from and there should be no arguing over having it fixed free of charge. I'm a bit surprised a car dealership would sell a car with this sort of problem, but it might simply be that the item was overlooked when the vehicle was being prepared for sale. The bottom line is that this is Mazda's problem, not yours and according to the warranty, it should be fixed for free. The only exception to that would be if the damaged part was caused by previous crash-damage, but even then, the second-hand car warranty offered by the dealer should cover such a pre-existing problem.