820-00239-09 - A1706 continues chime sound

Removing J501 I could see the fans running, starting with low speed and keep increasing to high speed, No other difference.Battery connectors also removed, Doesn't made any change.
SMC_LSOC_RST_L stays high (3.9V).
BUF_SMC_RESET_L - This I couldn't measure Because the test points are located on bottom layer where I don't have access when the board is mounted
Let me elaborate a little more ,

When I power up its goes to two different scenarios
Scenario1- it goes to loop with a chime sound. When it is in the loop I can see there is the backlight.
Scenario 2 - When I try to start No backlight, Slowly CPU heat increasing and the fan works after some time.


Staff member
Check CPU core voltage in both scenarios.
Disconnect devices one by one and try to identify if boots, but not looping.

Did you try PRAM reset?
Scenario1 - Loop
L7210 - PPVCC_S0_CPU - 1.078V
L7220 - PPVCC_S0_CPU - 1.078V

Scenario 2 - No response
L7210 - PPVCC_S0_CPU - 1.049V
L7220 - PPVCC_S0_CPU - 1.049V
One more input - I have a strong feeling that scenario 1 and scenario2 are related to temperature. If the heatsink is hot it doesn't go to loop. Or else it goes to loop.

Regarding the PRAM reset - I could hear only one chime when I press all four keys, Keep waiting for the second chime but it's not happening. But I could feel the heat on the heatsink.