Finding the Thevenin equivalent Resistance for circuit with voltage-dependent sources
Homework - no ready to copy solutions will be written, but some guidance.

Connect an ideal voltage source Us to AB and calculate how much current your circuit takes from it. You'll see that the current taken from Us is (QCF) x Us, where (QCF) is a quite complex formula which contains alpha, beta and the resistances R1, R2, R3.

This means that your circuit behaves like a resistor 1/(QCF). That's the Thevenin equivalent resistance. The Thevenin equivalent voltage of your circuit is zero.

This circuit has controlled sources. You cannot use solution methods which remove any of the controlled sources or any of the branches which control the sources. Make straight Kirchoff's current law equation where v2 is the unknown voltage. You can express v1 with Us and v2.