How can I take photos whenever the mirror lock up is effect

Wear suspenders, and hook onto a truck mirror whenever you can. Try to avoid low riders and ferraris....

Lights are flashing, if flash is not bad.auto diagnostic tool

Avoid camera shake. Watch your shutter speed. As a general rule, you should not allow this to fall to a speed slower than the reciprocal of your 35mm equivalent focal length. However, if you're using digital (or are willing to use your film up a bit quicker), you can try taking several shots in succession and hopefully one will have a satisfying level of sharpness. Turn on vibration reduction (also called "image stabilization", depending on the manufacturer), if you have it. When VR/IS is on, the lens element(s) or image sensor move so that the image stays in place when projected onto the sensor. As a result, camera motion is less likely to affect the sharpness of your photographs. Turn it on whenever the lighting conditions makes getting a sharp picture difficult. Keep it off when you're shooting on a tripod; it isn't needed and actually makes your photographs less sharp.
Use a shorter lens (or zoom out) and get closer. Remember that, according to the reciprocal rule of photography, reducing your focal length will give you less camera shake at any given shutter speed. Additionally, when you're using a variable-aperture zoom, you can often use a larger aperture with shorter focal lengths. Furthermore, getting closer might force you to be more creative when framing the picture.Use a tripod or a monopod If you're using an SLR and find yourself with so little light that you have no choice but to use long exposures, you might want to invest in a remote release cable. If your camera has a mirror lock-up (also called exposure delay mode), use it; this will stop the vibration from the mirror from affecting your images. Check your camera's manual to see what it's called. Mirror lock-up has two definitions; the other definition refers to when the mirrors and shutters move out of the way after you click the shutter button so that you can clean the image sensor without the sensor being active. If your camera doesn't have mirror lock-up, you can use the self timer.

{: ) Have someone control the power fold buttons, while you check closely the passenger mirror. If you can feel or hear even a faint hum of the motor while commanded, try giving it a little help, but don't force it if you think it doesn't have enough power to extend or retract itself. The motor could be really stuck or inoperative.
Sometimes when the mirror has been accidentally or manually folded, it needs to be reset by just pressing on the fold buttons a few rounds and let the mirrors fold by itself. Like an exercise.
If you hear the humming noise whenever the fold buttons are pressed, we can assume that the circuit on that side is ok since it is responding electrically, and that a jammed or stuck mechanism is preventing it to move.
If you don't feel or hear any humming, as in totally no sign of response, then there will be additional considerations before deciding to go for a replacement mirror. You will need to confirm if the fault is on the wirings, a door module, or the mirror motor itself. A scan tool test may be recommended for effective diagnosis.
The power fold mirror can be serviced as an assembly. So, goodluck.

Mirror lockup is probably enabled. You can disable it by going into Menu and then Custom Functions. Select Mirror lockup and disable it.

try to take a photo. if the mirror don't back down, switch off one more time. If the problem is still there you will have to put your camera to repair

Possibly the shaft has jammed. Follow this link for a source of good information: http://www.mapug-astronomy.net/AstroDesigns/MAPUG/ArhvList.htm

From their files:
The locking knob has a gear on the inside end of its shaft. It engages teeth on the outside edge of a large metal disk connected to the mechanism that locks the position of the mirror on the central baffle tube. Rotating the locking knob one direction rotates the large disk to tighten the collet on the central baffle. Reversing direction loosens it.
The teeth do not extend all the way around the large disk. So sometimes the locking knob gear jams to a stop before the lock is fully engaged. Soon after the GPS scopes first started shipping Buck Harley discovered that in such cases you can remove the locking knob with its shaft and gear, then reach in and rotate the large disk with your finger. Replacing the locking knob will now allow sufficient rotation to fully engage the lock. If you happen to move the large disk in the wrong direction, then just repeat the process and move the disk in the other direction.
You don't need to tighten the lock down hard. Just a little snug is enough. You should not attempt to use the coarse focus knob while the mirror is locked. Damage to the focusing mechanism could result.
This design is intended to precisely hold the mirror position. So, yes, it is meant to allow effective use of a separate guide scope by eliminating mirror flop when in the locked position.

Unfortunately, the mirror is part of a larger assembly. Like the D70, the mirror comes with the frame. To replace one, you are probably looking at close to 300$.

That being said, it is unlikely that the scratch will effect photos or performance of the camera

I have the SAME problem. I wrote to Canon and they told me to shut off the camera, take the battery out and wait 20 MINUTES! I can't WAIT that long, especially when I'm WORKING! I rely on this camera to work! Its annoying! Then they said if that doesn't work, to SEND IT IN and if its under warranty, they'll fix it for free.. if its NOT, then I have to pay for it. BUt the "technical team" will make the decision.