Charging indication issue

Recently I’m facing this issue. After connecting the charger to the device the charging indication (lightening bolt symbol, charger plugin sound, vibration) shows after 5- 8 secs. Then after 5 secs indication goes off for a sec and reappears. Then no interruptions, charging takes place continuously. I tried all the troubleshooting procedures like checking with different charger, factory reset, battery calibration but issue isn’t solved. But if i plugin when the mobile is off the indication showing immediately. I need to know whether it is a software issue or hardware issue. Google support asked me to sent the device to service center for checking to resolve the issue. As it takes 15 working days I’m thinking about it to send the device for check. Is it I’m the one facing this issue or few others too getting this. What your opinion regarding my issue, do i have the solution to fix this. Plz do reply. Thanks