How can I reset a Sony Wega tv without a remote

Good day.

This indication of your unit may have nothing to do with resetting it. It actually denotes that there is something wrong with the circuitry inside.

If you can open your unit and check for loose contacts particularly on the power supply section, horizontal section and on the system section.

Response is highly appreciated.

chris

You can only reset the TV when you have the remote as it requires holding down the RESET button on the remote control, then pressing the POWER button on the TV front panel. The TV will turn itself off, then back on again. Then release the RESET button.
Regarding your problem with the TV not staying on for 3 seconds, you can try unplugging the unit for at least an hour to perform a hard reset of the microprocessor. If the unit still doesn't stay on, you need to check the power supply or the entire board for any blown or bad capacitor, shorted terminals due to accumulation of dirt, or broken solders. It may be a tedious task and requires an electronic prowess to do.
Kudos and thanks for using Fixya.

sorry to tell you this but, the standby led is flashing because there is a shorted component most likely a diode or transister in the high voltage [horiz] output circuit.