I have a Samsung tv model un55h6203af. Attempted to update. Screen went off/on then off hasn't turned back on since. Umpteen hard resets later I'm still looking at a blinking led when powered on. No picture or sound just a blinking red led. Any suggestions

There is no one answer that fits all any number of defective parts can cause this, supplest you have it diagnosed, do not start buying parts.

as long as the boards cable connectors fit

Hope this blogs will be help full for you Bypass google lock on a samsung

https://www.unlockninja.com/blog/samsung-salaxy-s6-hard-reset-how-to-reset-galaxy-s6-without-losing-data/

On some models this reset may work, disconnect TV from outlet, press and hold the power button on the TV itself for about 30 seconds. Wait a minute, plug the set back in and press power button once.
Hope this helps cuz I don't know otherwise..but thought i'd share.

Fault at its main digital board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Pull up older posts. http://electronicshelponline.blogspot.com/ In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary. Do a Hard Reset first, and then check.
Before going further; try a hard reset first. If it does not help you, replace the main digital board. There are two methods to reset TVs. The first is simple to do; a Hard Reset. The other is somewhat skilled; is a Factory Reset (System Reset). To make it a hard reset, just unplug the TV from AC mains wall socket, and re-plug it back after 15 minutes or so. If you do this by overnight is better. This procedure will make it a hard reset. If you want to make it a system reset [Factory Reset]; you have to enter its service mode option, and select the factory reset option. If you wish to get some details; visit the site linked here.

If you have done the flashlight test and an image is present on the screen when the light is shined from behind then the backlight or the backlight regulator is defective, both should be replaced.

Fault at its main digital board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.
http://electro-medical.blogspot.com/

In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary.
Before going further; try a hard reset first. If it does not help you, replace the main digital board. There are two methods to reset TVs. The first is simple to do; a Hard Reset. The other is somewhat skilled; is a Factory Reset (System Reset). To make it a hard reset, just unplug the TV from AC mains wall socket, and re-plug it back after 15 minutes or so. If you do this by overnight is better. This procedure will make it a hard reset. If you want to make it a system reset [Factory Reset]; you have to enter its service mode option, and select the factory reset option. If you wish to get some details; visit the site linked here.

guess you may find some tip on onboard user guide - look in menu, or download manual from here




Samsung UN55H6203AF Manual

I attempted the above in order to hard reset my Europa i5500. However, it didn't work, and instead just went back to the "enter address/password" screen. I've attempted to connect to Kies, but to no avail, Kies doesn't register that the product is plugged in. I can get the phone onto download mode and emergency download mode, however neither are helping me much. Any suggestions?

Tries tv unplug,replug it back like about an hour later,that ur reset.If still getting the same result. The tv Tuner signal board is shorted and the causes,that why is shutting down.Tries websites like Shopjimmy.com,Ebay.com to buy a tv Tuner signal board for the replacement.