In materials known as failed insulators, electrical resistivity increases as temperature decreases, yet does not diverge—a phenomenon inconsistent with single-particle transport theories. We investigate the origin of this behavior by measuring shot noise in nanojunctions of nitrogen-doped $\beta$-$\mathrm{Ta}$, a prototypical failed insulator and an efficient spin-orbitronic material. Junctions as short as $8$ nm exhibit hot-electron shot noise, indicating strong electron interactions. We show that charge hopping mediated by electron interactions can account for the anomalous failed insulator properties. Based on our findings, we identify failed insulators as a distinct class of non-Fermi liquids, opening avenues for the studies of electron interactions and their applications.

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• Electron-phonon coupling
• Hopping transport
• Metal-insulator transition
• Shot noise
• Spin orbitronics
• Nanostructures
• Strongly correlated systems
• Non-Fermi-liquid theory