Hi @shikharihani ,
Have you tried the [https://www.download.p4c.philips.com/files/h/hf3520_60/hf3520_60_dfu_cfr.pdf|demonstration mode] (see p.22) to make sure that it still functions OK?
If still no good, then disconnect the power from the device and press and hold the lamp on/off button for a full 15 seconds and then release it.
Reconnect the power to the device and set it up again and check if it now works OK.
My thinking is that if there is a glitch in the device software that a power reset might restore it back to its default condition.