Searching for poles of a transfer function on the edge of stability

I just started using Mathematica and I am a bit stuck. I want to compute poles of transfer function that are on edge of stability i.e. Re[s] = 0 and I want to find for which RE that happens.

This is my transfer function:

I know such solutions exist because I've computed them manually using slider.

I've tried

sol1 = Solve[eq == 0, s];real = ComplexExpand[Re[st[[2]]]];sol2 = Solve[sol1 == 0, RE]

but I don't get anything. I wrote st[[2]]] because I get 3 poles, one is strictly real and always on lhs, and other two are complex conjugate that can pass on rhs, I hoped it will speed up stuff.

Edit

Full code:

Y = s*CF*(1 - (A0*s*τ1)/((1 + s*τ1)*(1 + s*τ2)));Yin = s*CE + 1/RE + Y;τ1n = 2.75*10^-07;τ2n = 7.52*10^-09;CFn = 18.951;CEn = 1;rep =   ReplaceAll[    Yin,     {CE -> CEn*10^-12, τ1 -> τ1n, τ2 -> τ2n, CF -> CFn*10^-12, A0 -> 2}]st = Solve[rep == 0, s];real = ComplexExpand[Re[st[[2]]]];sol = Solve[real == 0, RE]