I don't have one of these, so I can't repeat the procedure on a printer with a similarly mounted printhead like you have. While my guide covers the cleaning process, it doesn't cover the required disassembly to remove the printhead on permanently installed printers. I fixed this on a removable printhead model and it printed perfectly after I cleaned the head this way. The problem is related to a clog you can't easily get rid of without physically removing the printhead and soaking it in hot water. i suspect it is later, I will post update in future. I have a doubt whether this is actually blank ink or color ink is printing black color. However, when I print I can see black ink is getting printed.

The printer still says it has not detected the black cartridge (because the LED light for black cartridge is constantly on).

So after reading everyone post above, I also just applied clear masking tape on the complete contact points of the black cartridge and then inserted it. I figured out for it to accept the Color cartridge I have to Reset the printer (instruction for HP deskjet reset is available on internet), however, it never accepted black cartridge, it always show Black cartridge Indicator LED blinking meaning it is not recognizing the refilled cartridge. In my old printer, I could refill old cartridge & keep using printer, but this new HP DESKJET 2135 never accepts refilled cartridge. I hope helps other I hv been fighting with my printer for 6 mon now

Hp 2135 test print