Consider an endothermic reaction $\mathrm{X}⟶\mathrm{Y}$ with the activation energies ${\mathbf{E}}_b\text{ and }{\mathrm{E}}_f$ for the backward and forward reaction, respectively. In general

The activation energy of the backward reaction in an endothermic process will always be lower than the activation energy of the forward reaction. This is how the backlash will appear in your situation.

$\mathrm{A}+\text{ heat }\to \mathrm{B}$

The product will have more energy than the reactant, since heat is lost throughout the reaction. So, ${\mathrm{E}}_{\mathrm{b}}<{\mathrm{E}}_{\mathrm{f}}$