The structure of the $\Lambda(1405)$ resonance challenges hadron physicists for more than 40 years. It is controversially debated as either: an antikaon-nucleon bound state, a dynamically generated baryon resembling a meson-baryon molecule, or a resonance with $\Sigma\pi$ and $\mathrm{\bar{K}N}$ poles. Experimental results vary in line shape and peak position, depending on reaction type, making their interpretation very challenging.

The $\Lambda(1405)$ hyperon has been recently measured with the HADES detector in proton-proton collisions at 4.5 GeV beam energy. The new HADES electromagnetic calorimeter (ECAL) enables separation of $\Lambda(1405)$ from $\Sigma(1385)$ by measuring the decay channel $\Sigma^0\pi^0$, which is not allowed for the latter. Another recent advancement is the Forward Detector covering the very forward region ($0.5^\circ<\theta<6^\circ$), significantly increasing acceptance for hyperons. In this paper, we present analysis methods and preliminary results of the exclusive analysis in the channel $\mathrm{
pK^+\Lambda(1405) \to (\Sigma^0 (\to \Lambda^0 (\to p\pi^-) \gamma) \pi^0 (\to \gamma\gamma))}$.