Philips 42PF5521D will not switch on

These blinks [flashes] are fault indication (Error Codes). From the number of blinks occur at one time switch ON, you can get an idea about the faulty circuit stage inside it. This will make repair easy. These are called blinking codes. Make sure about the exact number of blinking of the standby/power led, by switching On & OFF the set, for at least two times. Count it carefully. If you wish to get some details, check the site linked here. It has details about blinking codes, and fault locating, to many popular brand TVs and other devices. Viewing it in "Mosaic" will make surf easy.
http://electronicshelponline.blogspot.com/
Blinking codes details to many popular brand TVs are given. Surf the site with patience. Unlike other brand sets, counting the number of blinks to Philips it different. It is not directly countable. Check the site for more details.

just replace bulging capacitors in the power supply board.

Check power board . Replace any capacitors that have domed tops.

Hallo! You might have a power trouble. Open the rear cover and take a look over the power board- that's the board where goes the alimentation cord. Look if there are not inflated the electrolytic capacitors, if yes, you must change them with the same type. Be careful with the polarity of the capacitors- you must solder them the same way as the old ones were.

If the green light comes on it sounds more like the inputs ... check that its on the right AV mode and the inputs are all plugged in properly and working.
Adam

Several capasitors in the power supply must be replaced.

Replace any domed capacitors on the power board.

Many problems with philips can be solved by doing a software update which is done with a flash drive in the USB port. The only problem is your model number dosen't show up on philips web site. You may want to try to email them from their site to ask why your's dosent exist.

http://www.p4c.philips.com/cgi-bin/dcbint/cpproduct_selector.pl?slg=AEN&scy=US

Those blinks [flashes] are fault indication (Error Codes). From the number of blinks occur at one time switch ON, you can get an idea about the faulty circuit section inside it. This will make repair easy. These are called blinking codes. Make sure about the exact number of blinking of the standby/power LED, by switching On & OFF the set, for at least two times. Count it carefully. If you wish to get some details, check the site linked here. It has details about blinking codes, and fault locating procedure, to many popular brand TVs and other devices.
http://homenol.blogspot.com/
http://electronicshelponline.blogspot.com/
If blinks continue without any pause, the main board is faulty.
Search the site by type in the "brand name" to your device, [Exclude the model number] in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.
Counting the number of blinks to Philips TVs is entirely different to that of other brand TVs. It is not a direct count procedure. The site have details about how to count the number of LED blinks [Fault Codes] to Philips brand TVs are given; along with details of the faulty circuit location.

Press and hold the menu button on the side and hold for five seconds, that will reset the tv ------------- do this after you have checked your manual for other troubleshooters, you know, the obvious 'correct channel i.e EXT1, EXT2, TV'