Canon 600D Flash Problem

My Canon 600D recently got back from repair (LCD Screen snapped) and is currently under warranty. However, there is a problem with the flash, it flicks up and flashes, but when you look at the picture it is very dark, as if the flash had been covered with my hand - and I assure you, it hasn't been.

Any help on how I could fix this? Should I send it back or is it a factory setting?

Thanks in advance for any help.

There are any number of reasons that might be happening...

A lens hood could be partially obscuring the built-in flash.

Various settings could be effecting the flash... such as FEC or Flash Exposure Compensation... which if it's dialed down will render a lot less flash output.

Using the camera in any of the Auto modes (Av, Tv, P) will make the flash "fill", with reduced power output. With "fill", the camera sets shutter and aperture to record ambient light, then the flash is fired only partially, to fill shadows as a secondary light source. Setting the camera to M will make for "full" flash, where the camera uses it as the primary light source.

Incorrect shutter speed.... Normally the camera is prevented from going higher than the max flash sync speed (probably 1/200 on your camera), but there might be settings that allow it to use higher speeds (High Speed Sync, sometimes called "FP" flash)... I dunno if your camera can do HSS with the built-in, however using this mode seriously limits any flash's reach.

Depending upon the distance to the subject, built-in flashes are pretty anemic, simply don't have much reach.

Read the manual.... it will have more info about using the flash on your particular camera and the various settings possible. I suspect that while working on your camera, it was set or reset in some way that effects the flash. It's less likely that there is something actually wrong with the flash (though it might have needed to be disassembled to change out the LCD screen).

But the best solution... First look in your manual for any way to turn off the built in flash and don't use it at all. I have a number of cameras with built in flashes and honestly can't recall the last time I used one. In over ten years using Canon cameras, I probably have used the built-in flash less than a half dozen times, only in an emergency when I didn't have a "real" flash to use. So, next thing is buy an accessory flash and use it with a flash bracket and off-camera shoe cord. The built-in is underpowered, in the worst possible place for redeye/eyeshine and ugly shadow effects, and it gobbles up the camera's battery charge. An accessory flash such as 580EX, 430EX, or even the small ones such as 270EX will give much nicer results, will be considerably more powerful (more reach), and has it's own battery sources so doesn't drain the camera's. If the Canon flashes are too pricey, there are various third party flashes that might be worth consideration.

If using an accessory flash, you can mount it directly in the camera's hot shoe (which has a microswitch to prevent the built-in from popping up, when anything is mounted in the hot shoe)... but I do recommend a simple flash bracket with off-camera cord to further move the flash away from the lens axis, making for even less chance of redeye/eyeshine and so that shadows are thrown down and behind the subject where they are less of an issue. Canon offers a shoe cord, but there are also much cheaper generic cords available (eBay and elsewhere). Canon doesn't offer a flash bracket, but there are any number of different ones available, some of the simpler, generic ones are pretty inexpensive. One I use cost about $20 US new, off eBay.

The most I've done is set the ISO to the highest on 'M' mode, and that improved ever so slightly.. I mean, I could make out what was there as opposed to complete darkness (and this is in a well-lit room!)

The camera isn't actually detecting the flash, even though it is going off a lot brighter than before it got back from repair.

Does that change anything?

if your using manual , what does the metering indicator show in the viewfinder with the flash on ?

The best thing is to try in in "green box" mode, it should expose correctly if there is nothing wrong with the flash