Seriously home brew is best...
That said an open faliure on a single LED can cause the whole string to fail.
Remember these are typical Chinese lights and you have to value their reliability and cost against a MH or T5...With extra electricity and periodical bulb replacement.
A quality Domestic LED fixture will cost more but will pay for itself in the long run.
The Bad LED is easily found with a continuity test and can be replaced or short circuited with solder...Short Circuiting these inexpensive fixtures may lead to a current imbalance between the other LEDs.
Replacement of the LED is a good option, replacing the fixture is a better option as what's going to fail next.
Bill