Is the $Λ$CDM Model in Crisis?

We present strong evidence for dynamical dark energy challenging the $Λ$CDM model. Several dark energy models are explored, including ω₀ωₐCDM, logarithmic, Exponential, JBP, and BA, along with non-flat cosmologies accounting for potential spatial curvature. Our analysis supports a flat Universe (Ωₖ ≈ 0). Using the Metropolis-Hastings MCMC algorithm, we analyze data from BAO of DESI DR2, Type Ia Supernovae, and CMB to constrain model parameters. We find strong evidence that ω≠ -1, with deviations from $Λ$CDM favoring dynamical dark energy consistent with the Quintom-B scenario (ω₀ > -1, ωₐ < 0, and ω₀ + ωₐ < -1). We also derive upper bounds on ∑ m_ν from CMB + DESI DR2. For $Λ$CDM we find ∑ m_ν< 0.066~eV, while for $ω$CDM it is ∑ m_ν< 0.075~eV. In o$Λ$CDM and o$ω$CDM the limits are ∑ m_ν< 0.263~eV and ∑ m_ν< 0.520~eV, respectively. For other models, including ω₀ωₐCDM, Logarithmic, Exponential, JBP, BA, and GEDE, the upper limits range from < 0.043~eV to < 0.127~eV. Constraints on the effective number of relativistic species, Neff, remain consistent with the standard value Neff = 3.044 for all models. Bayesian evidence shows that combining DES-SN5Y and Union3 SNe Ia with CMB + DESI DR2 reveals deviations from $Λ$CDM. Finally, while no model reaches the $5σ$ threshold, some show $> 3σ$ tensions with DES-SN5YR or Union3, hinting at cracks in the cosmological constant $Λ$.