Cyclone 4 JTAG programming issue

Recently, we faced the following problem during the JTAG programming for the chip EP4CE40F23. The chip suddenly was not recognized by the cable. At startup, the FPGA loads from the EPCS. The older EPCS jic file works fine. We wanted to change the code stored on the EPCS flash by the JTAG like we always did.

We noticed that the TDI pin voltage is not good. The JTAG debugging says that this pin may be shorted to gnd. We see small resistance value from this pin to the gnd using the Ohmeter.

Using the oscilloscope, we noticed that the voltage on this does not raise up to 2.5V like other working boards.

Thanks