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That sounds like a repeated-restart problem. Such problems occur in modern digital circuitry, when an attempt at total device startup is brought to a halt by a detected severe fault requiring reset or a detected severe fault requiring restart.
Either way, the device goes through the startup sequence again.
And if the startup sequence repeatedly fails, it is helpless as a device, until someone repairs it.
It might, just might possibly, be that you have either a power supply that is providing a (sensed or detected) wrong voltage level on one of its lines... or that there is a short loading down one of the lines later in the initialization (since the startup clock does actually appear), or that the Main Logic Board is defective.
How far does the startup clock get to, before the restart? that might possibly be indicative of the point of failure.