nRF51822 device isn't recognized

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nRF51822 and a PC were connected, nRFgoStudio was started and nRF5x Programming of a device manager was opened, the following comment comes out, and nRF51822 device can't be recognized.

"No device detected,orreadback protection may be set"

How should it be done to make sure that nRF51822 can be recognized?

Before starting nRFgoStudio, the following software was installed.

・Keil uVision IDE V5 ・nRFgo Studio ・Nordic nRF51 SDK 10.0.0 ・JLink V5.12f

[Susheel Nuguru]

download and install nrf command line tools here. After that connect and power your device, open command prompt and erase the chip using

nrfjprog -f nrf51 -e

That should clear the protection set in UICR register if it was set.