I have a sony bravia 55 inch rear projection tv. model no. KF-55E200A. when i turn it on it flashes green like normal but then starts flashing red. can you tell me what is wrong with it please

it is caused by a shortage in circuit board. it can be fixed by check and replace faulty components in main board.
if it is in warranty then claim it now,
if not then take it to a service shop.

COUNT THE # AND SEQUENCE OF THE BLINKING...CONTACT SONY TECH SUPPORT

I need to know if areas of the screen are green or blue with the color set to zero or with the set on a unused video input with nothing connected is the screen a uniform grey or black? This will point to what kind of trouble you have.

For Sony Model KF-60WE610, KF-50WE610, and KF-42WE610, the Diagnostic Code of power light indicator flashing 6 times green, then flashing 6 times red (6 red etc), means you need to replace part number A-1302-272A G1 BOARD, COMPLETE. See Sony Service Manual, 4. Chasis-1 at part Ref no. 103. The Power Board sits vertically in two slots on the left side of the electronics board. 4 wire connectors to remove when replacing. This component fits all 3 KF models listed above.

bad lamp , just replace the lamp and should be ok

Needs new lamp or the fan is out.

Ths 5 blinks usually indicate an AKB problem. There is a break in the video path. I'll look up your specific model and post the results here. Please update this if you wish to attempt the repair yourself.

Thanks,
Dan

Green flashing is normal. Red flashes are error codes. Count the error flashes.

3x - Lamp cover position or cover detect switch bad.
4x - One or more fans failed RPM test
5x - Lamp power supply/ballast failure
6x - Thermal fuse failed (usually)

There are a lot of sites that sell bulbs for those. Use a search engine and the model with the word bulb. Be aware that it may be the ballast though.

what model of Sony is it? On many of the Sony projectors, a 3 flash error code indicates the lamp is not properly seated/installed or the lamp door is not closed properly