U2415 flickering

Hi,

I bought a U2415 monitors last June (June 11, 2015) from Amazon. I have used them good but today one of the monitor was flickering. I replaced the monitor with good monitor the good monitor was OK. I tried the inputs HDMI1, HDMI2, mDP, all were same result(flickering).

Amazon only accept returns in 30 days from the purchase date. What can I do?

The problem monitor is  : 

S/N: CN-OPVJVW-74261-581-05ML    T

REV: A02

Date of Mfg: August 2015   90-130

Thanks!